Title: Performance of Concrete After Ten Years of Exposure in the Arctic Marine Environment
Author(s): M. H. Zhang, A. Bilodeau, and V. M. Malhotra
Publication: Symposium Paper
Appears on pages(s): 621-646
Keywords: aggregates; arctic marine environment; chloride-ion pen-etration;
compressive strength; concrete; fibre; fly ash; silica fume;
In 1986, as a part of CANMET’s on-going program on the long-term durability ofconcrete in marine environment, twelve concrete panels, each 3.7 meter long, were installed at a site at Nanisivik (Latitude 73’ North), Baffin Island, North West Territories, Canada. Six of the panels were made with normal-weight aggregate concrete, and the other six panels were made with concrete incorporating expanded shale lightweight aggregate. Other variables in the concrete mixtures included steel fibres, and the replacement of portland cement by fly ash, slag, silica fume, or a combination of fly ash and silica fume. The cement replacement levels used ranged from 10 % for silica fume to 50 % for ground granulated blast-furnace slag. The water-to-cementitious materials ratio of all these concretes ranged from 0.37 to 0.42. In 1996, visual examination was made and cores were taken from the concrete panels to determine the chloride content at various depths from the exposure surface. After 10 years of exposure in the Arctic marine environment, the panels made with normal weight aggregate showed very little mass loss on the surface due to ice abrasion, whereas panels made with lightweight aggregate seems to have some mass loss on the surface exposed to the tidal zone. The steel fibre-reinforced panels appear to have less damage and cracking than the corresponding ones without fibres. Concrete incorporating supplementary cementing materials such as fly ash, silica fume, slag, or a combination of fly ash and silica fume generally had better resistance to the penetration of chloride ions compared with corresponding control portland cement concrete of similar water-to- cementitious materials ratio. In general, the concentration of chloride ions in fibre-reinforced concrete was similar to or lower than those of the corresponding non-fibre-reinforced concrete exposed. For the non-fibre- reinforced portland cement concrete, the use of either normal weight limestone aggregate or expanded shale lightweight aggregate did not seem to significantly affect the resistance of the concrete to the chloride-ion penetration. However, fibre-reinforced portland cement concrete made with lightweight aggregate appears to have lower chloride-ion content than that made with normal weight aggregate.